Adding metformin at bedtime is usually not necessary, and by taking metformin at bedtime you can prevent high fasting blood glucose. Clinically, some diabetic patients have stable blood glucose control during the day, but in the early morning will have a rise in fasting blood glucose, you can consider taking an additional tablet of metformin before bedtime. It is not necessary to add meals after taking additional medication, because adding meals will lead to a further rise in blood glucose, affecting blood glucose control. After an early change in medication, it is important to monitor fasting and postprandial blood glucose several times to determine the status of blood glucose control. Common adverse reactions to metformin include gastrointestinal reactions, skin allergies and lactic acidosis, and it is contraindicated in patients with severe complications, alcoholism, and severe renal insufficiency. The medication should be taken under the supervision of a doctor, and you should not change the dose on your own.